/* Copyright 2008-2012 Codership Oy <http://www.codership.com>

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

#include "wsrep_sst.h"

#include <mysqld.h>
#include <m_ctype.h>
#include <my_sys.h>
#include <strfunc.h>
#include <sql_class.h>
#include <set_var.h>
#include <sql_acl.h>
#include <sql_reload.h>
#include <sql_parse.h>
#include "wsrep_priv.h"
#include "wsrep_utils.h"
#include <cstdio>
#include <cstdlib>

char wsrep_defaults_file[FN_REFLEN * 2 + 10 +
                         sizeof(WSREP_SST_OPT_CONF) +
                         sizeof(WSREP_SST_OPT_EXTRA_CONF)] = {0};

const char* wsrep_sst_method          = WSREP_SST_DEFAULT;
const char* wsrep_sst_receive_address = WSREP_SST_ADDRESS_AUTO;
const char* wsrep_sst_donor           = "";
      char* wsrep_sst_auth            = NULL;

// container for real auth string
static const char* sst_auth_real      = NULL;
my_bool wsrep_sst_donor_rejects_queries = FALSE;

bool wsrep_sst_method_check (sys_var *self, THD* thd, set_var* var)
{
  if ((! var->save_result.string_value.str) ||
      (var->save_result.string_value.length == 0 ))
  {
    my_error(ER_WRONG_VALUE_FOR_VAR, MYF(0), var->var->name.str,
             var->save_result.string_value.str ?
             var->save_result.string_value.str : "NULL");
    return 1;
  }

  return 0;
}

bool wsrep_sst_method_update (sys_var *self, THD* thd, enum_var_type type)
{
    return 0;
}


static void make_wsrep_defaults_file()
{
  if (!wsrep_defaults_file[0])
  {
    char *ptr= wsrep_defaults_file;
    char *end= ptr + sizeof(wsrep_defaults_file);
    if (my_defaults_file)
      ptr= strxnmov(ptr, end - ptr,
                    WSREP_SST_OPT_CONF, " '", my_defaults_file, "' ", NULL);

    if (my_defaults_extra_file)
      ptr= strxnmov(ptr, end - ptr,
                    WSREP_SST_OPT_EXTRA_CONF, " '", my_defaults_extra_file, "' ", NULL);
  }
}


// TODO: Improve address verification.
static bool sst_receive_address_check (const char* str)
{
    if (!strncasecmp(str, "127.0.0.1", strlen("127.0.0.1")) ||
        !strncasecmp(str, "localhost", strlen("localhost")))
    {
        return 1;
    }

    return 0;
}

bool  wsrep_sst_receive_address_check (sys_var *self, THD* thd, set_var* var)
{
  char addr_buf[FN_REFLEN];

  if ((! var->save_result.string_value.str) ||
      (var->save_result.string_value.length > (FN_REFLEN - 1))) // safety
  {
    goto err;
  }

  memcpy(addr_buf, var->save_result.string_value.str,
         var->save_result.string_value.length);
  addr_buf[var->save_result.string_value.length]= 0;

  if (sst_receive_address_check(addr_buf))
  {
    goto err;
  }

  return 0;

err:
  my_error(ER_WRONG_VALUE_FOR_VAR, MYF(0), var->var->name.str,
           var->save_result.string_value.str ?
           var->save_result.string_value.str : "NULL");
  return 1;
}

bool wsrep_sst_receive_address_update (sys_var *self, THD* thd,
                                       enum_var_type type)
{
    return 0;
}

bool wsrep_sst_auth_check (sys_var *self, THD* thd, set_var* var)
{
    return 0;
}

static bool sst_auth_real_set (const char* value)
{
  const char* v= NULL;

  if (value)
  {
    v= my_strdup(value, MYF(0));
  }
  else                                          // its NULL
  {
    wsrep_sst_auth_free();
    return 0;
  }

  if (v)
  {
    // set sst_auth_real
    if (sst_auth_real) { my_free((void *) sst_auth_real); }
    sst_auth_real = v;

    // mask wsrep_sst_auth
    if (strlen(sst_auth_real))
    {
      if (wsrep_sst_auth) { my_free((void*) wsrep_sst_auth); }
      wsrep_sst_auth= my_strdup(WSREP_SST_AUTH_MASK, MYF(0));
    }
    return 0;
  }
  return 1;
}

void wsrep_sst_auth_free()
{
  if (wsrep_sst_auth) { my_free((void *) wsrep_sst_auth); }
  if (sst_auth_real) { my_free((void *) sst_auth_real); }
  wsrep_sst_auth= NULL;
  sst_auth_real= NULL;
}

bool wsrep_sst_auth_update (sys_var *self, THD* thd, enum_var_type type)
{
    return sst_auth_real_set (wsrep_sst_auth);
}

void wsrep_sst_auth_init (const char* value)
{
    if (wsrep_sst_auth == value) wsrep_sst_auth = NULL;
    if (value) sst_auth_real_set (value);
}

bool  wsrep_sst_donor_check (sys_var *self, THD* thd, set_var* var)
{
  return 0;
}

bool wsrep_sst_donor_update (sys_var *self, THD* thd, enum_var_type type)
{
    return 0;
}

static wsrep_uuid_t cluster_uuid = WSREP_UUID_UNDEFINED;

bool wsrep_before_SE()
{
  return (wsrep_provider != NULL
          && strcmp (wsrep_provider,   WSREP_NONE)
          && strcmp (wsrep_sst_method, WSREP_SST_SKIP)
          && strcmp (wsrep_sst_method, WSREP_SST_MYSQLDUMP));
}

static bool            sst_complete = false;
static bool            sst_needed   = false;

void wsrep_sst_grab ()
{
  WSREP_INFO("wsrep_sst_grab()");
  if (mysql_mutex_lock (&LOCK_wsrep_sst)) abort();
  sst_complete = false;
  mysql_mutex_unlock (&LOCK_wsrep_sst);
}

// Wait for end of SST
bool wsrep_sst_wait ()
{
  if (mysql_mutex_lock (&LOCK_wsrep_sst)) abort();
  while (!sst_complete)
  {
    WSREP_INFO("Waiting for SST to complete.");
    mysql_cond_wait (&COND_wsrep_sst, &LOCK_wsrep_sst);
  }

  if (local_seqno >= 0)
  {
    WSREP_INFO("SST complete, seqno: %lld", (long long) local_seqno);
  }
  else
  {
    WSREP_ERROR("SST failed: %d (%s)",
                int(-local_seqno), strerror(-local_seqno));
  }

  mysql_mutex_unlock (&LOCK_wsrep_sst);

  return (local_seqno >= 0);
}

// Signal end of SST
void wsrep_sst_complete (const wsrep_uuid_t* sst_uuid,
                         wsrep_seqno_t       sst_seqno,
                         bool                needed)
{
  if (mysql_mutex_lock (&LOCK_wsrep_sst)) abort();
  if (!sst_complete)
  {
    sst_complete = true;
    sst_needed   = needed;
    local_uuid   = *sst_uuid;
    local_seqno  = sst_seqno;
    mysql_cond_signal (&COND_wsrep_sst);
  }
  else
  {
    /* This can happen when called from wsrep_synced_cb().
       At the moment there is no way to check there
       if main thread is still waiting for signal,
       so wsrep_sst_complete() is called from there
       each time wsrep_ready changes from FALSE -> TRUE.
    */
    WSREP_DEBUG("Nobody is waiting for SST.");
  }
  mysql_mutex_unlock (&LOCK_wsrep_sst);
}

void wsrep_sst_received (wsrep_t*            const wsrep,
                         const wsrep_uuid_t* const uuid,
                         wsrep_seqno_t       const seqno,
                         const void*         const state,
                         size_t              const state_len)
{
    int const rcode(seqno < 0 ? seqno : 0);
    wsrep_gtid_t const state_id = {
        *uuid, (rcode ? WSREP_SEQNO_UNDEFINED : seqno)
    };
#ifdef GTID_SUPPORT
    wsrep_init_sidno(state_id.uuid);
#endif /* GTID_SUPPORT */
    wsrep->sst_received(wsrep, &state_id, state, state_len, rcode);
}

// Let applier threads to continue
void wsrep_sst_continue ()
{
  if (sst_needed)
  {
    WSREP_INFO("Signalling provider to continue.");
    wsrep_sst_received (wsrep, &local_uuid, local_seqno, NULL, 0);
  }
}

struct sst_thread_arg
{
  const char*     cmd;
  int             err;
  char*           ret_str;
  mysql_mutex_t   lock;
  mysql_cond_t    cond;

  sst_thread_arg (const char* c) : cmd(c), err(-1), ret_str(0)
  {
    mysql_mutex_init(key_LOCK_wsrep_sst_thread, &lock, MY_MUTEX_INIT_FAST);
    mysql_cond_init(key_COND_wsrep_sst_thread, &cond, NULL);
  }

  ~sst_thread_arg()
  {
    mysql_cond_destroy  (&cond);
    mysql_mutex_unlock  (&lock);
    mysql_mutex_destroy (&lock);
  }
};

static int sst_scan_uuid_seqno (const char* str,
                                wsrep_uuid_t* uuid, wsrep_seqno_t* seqno)
{
  int offt = wsrep_uuid_scan (str, strlen(str), uuid);
  if (offt > 0 && strlen(str) > (unsigned int)offt && ':' == str[offt])
  {
    *seqno = strtoll (str + offt + 1, NULL, 10);
    if (*seqno != LLONG_MAX || errno != ERANGE)
    {
      return 0;
    }
  }

  WSREP_ERROR("Failed to parse uuid:seqno pair: '%s'", str);
  return EINVAL;
}

// get rid of trailing \n
static char* my_fgets (char* buf, size_t buf_len, FILE* stream)
{
   char* ret= fgets (buf, buf_len, stream);

   if (ret)
   {
       size_t len = strlen(ret);
       if (len > 0 && ret[len - 1] == '\n') ret[len - 1] = '\0';
   }

   return ret;
}

/*
  Generate opt_binlog_opt_val for sst_donate_other(), sst_prepare_other().

  Returns zero on success, negative error code otherwise.

  String containing binlog name is stored in param ret if binlog is enabled
  and GTID mode is on, otherwise empty string. Returned string should be
  freed with my_free().
 */
static int generate_binlog_opt_val(char** ret)
{
  DBUG_ASSERT(ret);
  *ret= NULL;
  if (opt_bin_log)
  {
    assert(opt_bin_logname);
    *ret= strcmp(opt_bin_logname, "0") ?
        my_strdup(opt_bin_logname, MYF(0)) : my_strdup("", MYF(0));
  }
  else
  {
    *ret= my_strdup("", MYF(0));
  }
  if (!*ret) return -ENOMEM;
  return 0;
}

static void* sst_joiner_thread (void* a)
{
  sst_thread_arg* arg= (sst_thread_arg*) a;
  int err= 1;

  {
    const char magic[] = "ready";
    const size_t magic_len = sizeof(magic) - 1;
    const size_t out_len = 512;
    char out[out_len];

    WSREP_INFO("Running: '%s'", arg->cmd);

    wsp::process proc (arg->cmd, "r");

    if (proc.pipe() && !proc.error())
    {
      const char* tmp= my_fgets (out, out_len, proc.pipe());

      if (!tmp || strlen(tmp) < (magic_len + 2) ||
          strncasecmp (tmp, magic, magic_len))
      {
        WSREP_ERROR("Failed to read '%s <addr>' from: %s\n\tRead: '%s'",
                    magic, arg->cmd, tmp);
        proc.wait();
        if (proc.error()) err = proc.error();
      }
      else
      {
        err = 0;
      }
    }
    else
    {
      err = proc.error();
      WSREP_ERROR("Failed to execute: %s : %d (%s)",
                  arg->cmd, err, strerror(err));
    }

    // signal sst_prepare thread with ret code,
    // it will go on sending SST request
    mysql_mutex_lock   (&arg->lock);
    if (!err)
    {
      arg->ret_str = strdup (out + magic_len + 1);
      if (!arg->ret_str) err = ENOMEM;
    }
    arg->err = -err;
    mysql_cond_signal  (&arg->cond);
    mysql_mutex_unlock (&arg->lock); //! @note arg is unusable after that.

    if (err) return NULL; /* lp:808417 - return immediately, don't signal
                           * initializer thread to ensure single thread of
                           * shutdown. */

    wsrep_uuid_t  ret_uuid  = WSREP_UUID_UNDEFINED;
    wsrep_seqno_t ret_seqno = WSREP_SEQNO_UNDEFINED;

    // in case of successfull receiver start, wait for SST completion/end
    char* tmp = my_fgets (out, out_len, proc.pipe());

    proc.wait();
    err= EINVAL;

    if (!tmp)
    {
      WSREP_ERROR("Failed to read uuid:seqno from joiner script.");
      if (proc.error()) err = proc.error();
    }
    else
    {
      err= sst_scan_uuid_seqno (out, &ret_uuid, &ret_seqno);
    }

    if (err)
    {
      ret_uuid=  WSREP_UUID_UNDEFINED;
      ret_seqno= -err;
    }

    // Tell initializer thread that SST is complete
    wsrep_sst_complete (&ret_uuid, ret_seqno, true);
  }

  return NULL;
}

static ssize_t sst_prepare_other (const char*  method,
                                  const char*  addr_in,
                                  const char** addr_out)
{
  ssize_t cmd_len= 1024;
  char    cmd_str[cmd_len];
  const char* sst_dir= mysql_real_data_home;
  const char* binlog_opt= "";
  char* binlog_opt_val= NULL;

  int ret;
  if ((ret= generate_binlog_opt_val(&binlog_opt_val)))
  {
    WSREP_ERROR("sst_prepare_other(): generate_binlog_opt_val() failed: %d",
                ret);
    return ret;
  }
  if (strlen(binlog_opt_val)) binlog_opt= WSREP_SST_OPT_BINLOG;

  make_wsrep_defaults_file();

  ret= snprintf (cmd_str, cmd_len,
                 "wsrep_sst_%s "
                 WSREP_SST_OPT_ROLE" 'joiner' "
                 WSREP_SST_OPT_ADDR" '%s' "
                 WSREP_SST_OPT_AUTH" '%s' "
                 WSREP_SST_OPT_DATA" '%s' "
                 " %s "
                 WSREP_SST_OPT_PARENT" '%d'"
                 " %s '%s' ",
                 method, addr_in, (sst_auth_real) ? sst_auth_real : "",
                 sst_dir, wsrep_defaults_file, (int)getpid(),
                 binlog_opt, binlog_opt_val);
  my_free(binlog_opt_val);

  if (ret < 0 || ret >= cmd_len)
  {
    WSREP_ERROR("sst_prepare_other(): snprintf() failed: %d", ret);
    return (ret < 0 ? ret : -EMSGSIZE);
  }

  pthread_t tmp;
  sst_thread_arg arg(cmd_str);
  mysql_mutex_lock (&arg.lock);
  ret = pthread_create (&tmp, NULL, sst_joiner_thread, &arg);
  if (ret)
  {
    WSREP_ERROR("sst_prepare_other(): pthread_create() failed: %d (%s)",
                ret, strerror(ret));
    return ret;
  }
  mysql_cond_wait (&arg.cond, &arg.lock);

  *addr_out= arg.ret_str;

  if (!arg.err)
    ret = strlen(*addr_out);
  else
  {
    assert (arg.err < 0);
    ret = arg.err;
  }

  pthread_detach (tmp);

  return ret;
}

extern uint  mysqld_port;

/*! Just tells donor where to send mysqldump */
static ssize_t sst_prepare_mysqldump (const char*  addr_in,
                                      const char** addr_out)
{
  ssize_t ret = strlen (addr_in);

  if (!strrchr(addr_in, ':'))
  {
    ssize_t s = ret + 7;
    char* tmp = (char*) malloc (s);

    if (tmp)
    {
      ret= snprintf (tmp, s, "%s:%u", addr_in, mysqld_port);

      if (ret > 0 && ret < s)
      {
        *addr_out= tmp;
        return ret;
      }
      if (ret > 0) /* buffer too short */ ret = -EMSGSIZE;
      free (tmp);
    }
    else {
      ret= -ENOMEM;
    }

    WSREP_ERROR ("Could not prepare state transfer request: "
                 "adding default port failed: %zd.", ret);
  }
  else {
    *addr_out= addr_in;
  }

  return ret;
}

static bool SE_initialized = false;

ssize_t wsrep_sst_prepare (void** msg)
{
  const ssize_t ip_max= 256;
  char ip_buf[ip_max];
  const char* addr_in=  NULL;
  const char* addr_out= NULL;

  if (!strcmp(wsrep_sst_method, WSREP_SST_SKIP))
  {
    ssize_t ret = strlen(WSREP_STATE_TRANSFER_TRIVIAL) + 1;
    *msg = strdup(WSREP_STATE_TRANSFER_TRIVIAL);
    if (!msg)
    {
      WSREP_ERROR("Could not allocate %zd bytes for state request", ret);
      unireg_abort(1);
    }
    return ret;
  }

  // Figure out SST address. Common for all SST methods
  if (wsrep_sst_receive_address &&
    strcmp (wsrep_sst_receive_address, WSREP_SST_ADDRESS_AUTO))
  {
    addr_in= wsrep_sst_receive_address;
  }
  else if (wsrep_node_address && strlen(wsrep_node_address))
  {
    const char* const colon= strchr (wsrep_node_address, ':');
    if (colon)
    {
      ptrdiff_t const len= colon - wsrep_node_address;
      strncpy (ip_buf, wsrep_node_address, len);
      ip_buf[len]= '\0';
      addr_in= ip_buf;
    }
    else
    {
      addr_in= wsrep_node_address;
    }
  }
  else
  {
    ssize_t ret= wsrep_guess_ip (ip_buf, ip_max);

    if (ret && ret < ip_max)
    {
      addr_in= ip_buf;
    }
    else
    {
      WSREP_ERROR("Could not prepare state transfer request: "
                  "failed to guess address to accept state transfer at. "
                  "wsrep_sst_receive_address must be set manually.");
      unireg_abort(1);
    }
  }

  ssize_t addr_len= -ENOSYS;
  if (!strcmp(wsrep_sst_method, WSREP_SST_MYSQLDUMP))
  {
    addr_len= sst_prepare_mysqldump (addr_in, &addr_out);
    if (addr_len < 0) unireg_abort(1);
  }
  else
  {
    /*! A heuristic workaround until we learn how to stop and start engines */
    if (SE_initialized)
    {
      // we already did SST at initializaiton, now engines are running
      // sql_print_information() is here because the message is too long
      // for WSREP_INFO.
      sql_print_information ("WSREP: "
                 "You have configured '%s' state snapshot transfer method "
                 "which cannot be performed on a running server. "
                 "Wsrep provider won't be able to fall back to it "
                 "if other means of state transfer are unavailable. "
                 "In that case you will need to restart the server.",
                 wsrep_sst_method);
      *msg = 0;
      return 0;
    }

    addr_len = sst_prepare_other (wsrep_sst_method, addr_in, &addr_out);
    if (addr_len < 0)
    {
      WSREP_ERROR("Failed to prepare for '%s' SST. Unrecoverable.",
                   wsrep_sst_method);
      unireg_abort(1);
    }
  }

  size_t const method_len(strlen(wsrep_sst_method));
  size_t const msg_len   (method_len + addr_len + 2 /* + auth_len + 1*/);

  *msg = malloc (msg_len);
  if (NULL != *msg) {
    char* const method_ptr(reinterpret_cast<char*>(*msg));
    strcpy (method_ptr, wsrep_sst_method);
    char* const addr_ptr(method_ptr + method_len + 1);
    strcpy (addr_ptr, addr_out);

    WSREP_INFO ("Prepared SST request: %s|%s", method_ptr, addr_ptr);
  }
  else {
    WSREP_ERROR("Failed to allocate SST request of size %zu. Can't continue.",
                msg_len);
    unireg_abort(1);
  }

  if (addr_out != addr_in) /* malloc'ed */ free ((char*)addr_out);

  return msg_len;
}

// helper method for donors
static int sst_run_shell (const char* cmd_str, int max_tries)
{
  int ret = 0;

  for (int tries=1; tries <= max_tries; tries++)
  {
    wsp::process proc (cmd_str, "r");

    if (NULL != proc.pipe())
    {
      proc.wait();
    }

    if ((ret = proc.error()))
    {
      WSREP_ERROR("Try %d/%d: '%s' failed: %d (%s)",
                  tries, max_tries, proc.cmd(), ret, strerror(ret));
      sleep (1);
    }
    else
    {
      WSREP_DEBUG("SST script successfully completed.");
      break;
    }
  }

  return -ret;
}

static void sst_reject_queries(my_bool close_conn)
{
    wsrep_ready_set (FALSE); // this will be resotred when donor becomes synced
    WSREP_INFO("Rejecting client queries for the duration of SST.");
    if (TRUE == close_conn) wsrep_close_client_connections(FALSE);
}

static int sst_mysqldump_check_addr (const char* user, const char* pswd,
                                     const char* host, const char* port)
{
  return 0;
}

static int sst_donate_mysqldump (const char*         addr,
                                 const wsrep_uuid_t* uuid,
                                 const char*         uuid_str,
                                 wsrep_seqno_t       seqno,
                                 bool                bypass)
{
  size_t host_len;
  const char* port = strchr (addr, ':');

  if (port)
  {
    port += 1;
    host_len = port - addr;
  }
  else
  {
    port = "";
    host_len = strlen (addr) + 1;
  }

  char host[host_len];

  strncpy (host, addr, host_len - 1);
  host[host_len - 1] = '\0';

  const char* auth = sst_auth_real;
  const char* pswd = (auth) ? strchr (auth, ':') : NULL;
  size_t user_len;

  if (pswd)
  {
    pswd += 1;
    user_len = pswd - auth;
  }
  else
  {
    pswd = "";
    user_len = (auth) ? strlen (auth) + 1 : 1;
  }

  char user[user_len];

  strncpy (user, (auth) ? auth : "", user_len - 1);
  user[user_len - 1] = '\0';

  int ret = sst_mysqldump_check_addr (user, pswd, host, port);
  if (!ret)
  {
    size_t cmd_len= 1024;
    char   cmd_str[cmd_len];

    if (!bypass && wsrep_sst_donor_rejects_queries) sst_reject_queries(TRUE);

    make_wsrep_defaults_file();

    snprintf (cmd_str, cmd_len,
              "wsrep_sst_mysqldump "
              WSREP_SST_OPT_USER" '%s' "
              WSREP_SST_OPT_PSWD" '%s' "
              WSREP_SST_OPT_HOST" '%s' "
              WSREP_SST_OPT_PORT" '%s' "
              WSREP_SST_OPT_LPORT" '%u' "
              WSREP_SST_OPT_SOCKET" '%s' "
              " %s "
              WSREP_SST_OPT_GTID" '%s:%lld'"
              "%s",
              user, pswd, host, port, mysqld_port, mysqld_unix_port,
              wsrep_defaults_file, uuid_str,
              (long long)seqno, bypass ? " "WSREP_SST_OPT_BYPASS : "");

    WSREP_DEBUG("Running: '%s'", cmd_str);

    ret= sst_run_shell (cmd_str, 3);
  }

  wsrep_gtid_t const state_id = { *uuid, (ret ? WSREP_SEQNO_UNDEFINED : seqno)};

  wsrep->sst_sent (wsrep, &state_id, ret);

  return ret;
}

wsrep_seqno_t wsrep_locked_seqno= WSREP_SEQNO_UNDEFINED;

static int run_sql_command(THD *thd, const char *query)
{
  thd->set_query((char *)query, strlen(query));

  Parser_state ps;
  if (ps.init(thd, thd->query(), thd->query_length()))
  {
    WSREP_ERROR("SST query: %s failed", query);
    return -1;
  }

  mysql_parse(thd, thd->query(), thd->query_length(), &ps);
  if (thd->is_error())
  {
    int const err= thd->get_stmt_da()->sql_errno();
    WSREP_WARN ("error executing '%s': %d (%s)%s",
                query, err, thd->get_stmt_da()->message(),
                err == ER_UNKNOWN_SYSTEM_VARIABLE ?
                ". Was mysqld built with --with-innodb-disallow-writes ?" : "");
    thd->clear_error();
    return -1;
  }
  return 0;
}

static int sst_flush_tables(THD* thd)
{
  WSREP_INFO("Flushing tables for SST...");

  int err;
  int not_used;
  CHARSET_INFO *current_charset;

  current_charset = thd->variables.character_set_client;

  if (!is_supported_parser_charset(current_charset))
  {
      /* Do not use non-supported parser character sets */
      WSREP_WARN("Current client character set is non-supported parser character set: %s", current_charset->csname);
      thd->variables.character_set_client = &my_charset_latin1;
      WSREP_WARN("For SST temporally setting character set to : %s",
	      my_charset_latin1.csname);
  }

  if (run_sql_command(thd, "FLUSH TABLES WITH READ LOCK"))
  {
    WSREP_ERROR("Failed to flush and lock tables");
    err = -1;
  }
  else
  {
    /* make sure logs are flushed after global read lock acquired */
    err= reload_acl_and_cache(thd, REFRESH_ENGINE_LOG | REFRESH_BINARY_LOG,
			      (TABLE_LIST*) 0, &not_used);
  }

  thd->variables.character_set_client = current_charset;


  if (err)
  {
    WSREP_ERROR("Failed to flush tables: %d (%s)", err, strerror(err));
  }
  else
  {
    WSREP_INFO("Tables flushed.");
    const char base_name[]= "tables_flushed";
    ssize_t const full_len= strlen(mysql_real_data_home) + strlen(base_name)+2;
    char real_name[full_len];
    sprintf(real_name, "%s/%s", mysql_real_data_home, base_name);
    char tmp_name[full_len + 4];
    sprintf(tmp_name, "%s.tmp", real_name);

    FILE* file= fopen(tmp_name, "w+");
    if (0 == file)
    {
      err= errno;
      WSREP_ERROR("Failed to open '%s': %d (%s)", tmp_name, err,strerror(err));
    }
    else
    {
      fprintf(file, "%s:%lld\n",
              wsrep_cluster_state_uuid, (long long)wsrep_locked_seqno);
      fsync(fileno(file));
      fclose(file);
      if (rename(tmp_name, real_name) == -1)
      {
        err= errno;
        WSREP_ERROR("Failed to rename '%s' to '%s': %d (%s)",
                     tmp_name, real_name, err,strerror(err));
      }
    }
  }

  return err;
}

static void sst_disallow_writes (THD* thd, bool yes)
{
  char query_str[64] = { 0, };
  ssize_t const query_max = sizeof(query_str) - 1;
  CHARSET_INFO *current_charset;

  current_charset = thd->variables.character_set_client;

  if (!is_supported_parser_charset(current_charset))
  {
      /* Do not use non-supported parser character sets */
      WSREP_WARN("Current client character set is non-supported parser character set: %s", current_charset->csname);
      thd->variables.character_set_client = &my_charset_latin1;
      WSREP_WARN("For SST temporally setting character set to : %s",
	      my_charset_latin1.csname);
  }

  snprintf (query_str, query_max, "SET GLOBAL innodb_disallow_writes=%d",
            yes ? 1 : 0);

  if (run_sql_command(thd, query_str))
  {
    WSREP_ERROR("Failed to disallow InnoDB writes");
  }
  thd->variables.character_set_client = current_charset;
}

static void* sst_donor_thread (void* a)
{
  sst_thread_arg* arg= (sst_thread_arg*)a;

  WSREP_INFO("Running: '%s'", arg->cmd);

  int  err= 1;
  bool locked= false;

  const char*  out= NULL;
  const size_t out_len= 128;
  char         out_buf[out_len];

  wsrep_uuid_t  ret_uuid= WSREP_UUID_UNDEFINED;
  wsrep_seqno_t ret_seqno= WSREP_SEQNO_UNDEFINED; // seqno of complete SST

  wsp::thd thd(FALSE); // we turn off wsrep_on for this THD so that it can
                       // operate with wsrep_ready == OFF
  wsp::process proc(arg->cmd, "r");

  err= proc.error();

/* Inform server about SST script startup and release TO isolation */
  mysql_mutex_lock   (&arg->lock);
  arg->err = -err;
  mysql_cond_signal  (&arg->cond);
  mysql_mutex_unlock (&arg->lock); //! @note arg is unusable after that.

  if (proc.pipe() && !err)
  {
wait_signal:
    out= my_fgets (out_buf, out_len, proc.pipe());

    if (out)
    {
      const char magic_flush[]= "flush tables";
      const char magic_cont[]= "continue";
      const char magic_done[]= "done";

      if (!strcasecmp (out, magic_flush))
      {
        err= sst_flush_tables (thd.ptr);
        if (!err)
        {
          sst_disallow_writes (thd.ptr, true);
          locked= true;
          goto wait_signal;
        }
      }
      else if (!strcasecmp (out, magic_cont))
      {
        if (locked)
        {
          sst_disallow_writes (thd.ptr, false);
          thd.ptr->global_read_lock.unlock_global_read_lock (thd.ptr);
          locked= false;
        }
        err=  0;
        goto wait_signal;
      }
      else if (!strncasecmp (out, magic_done, strlen(magic_done)))
      {
        err= sst_scan_uuid_seqno (out + strlen(magic_done) + 1,
                                  &ret_uuid, &ret_seqno);
      }
      else
      {
        WSREP_WARN("Received unknown signal: '%s'", out);
      }
    }
    else
    {
      WSREP_ERROR("Failed to read from: %s", proc.cmd());
      proc.wait();
    }
    if (!err && proc.error()) err= proc.error();
  }
  else
  {
    WSREP_ERROR("Failed to execute: %s : %d (%s)",
                proc.cmd(), err, strerror(err));
  }

  if (locked) // don't forget to unlock server before return
  {
    sst_disallow_writes (thd.ptr, false);
    thd.ptr->global_read_lock.unlock_global_read_lock (thd.ptr);
  }

  // signal to donor that SST is over
  struct wsrep_gtid const state_id = {
      ret_uuid, err ? WSREP_SEQNO_UNDEFINED : ret_seqno
  };
  wsrep->sst_sent (wsrep, &state_id, -err);
  proc.wait();

  return NULL;
}



static int sst_donate_other (const char*   method,
                             const char*   addr,
                             const char*   uuid,
                             wsrep_seqno_t seqno,
                             bool          bypass)
{
  ssize_t cmd_len = 4096;
  char    cmd_str[cmd_len];
  const char* binlog_opt= "";
  char* binlog_opt_val= NULL;

  int ret;
  if ((ret= generate_binlog_opt_val(&binlog_opt_val)))
  {
    WSREP_ERROR("sst_donate_other(): generate_binlog_opt_val() failed: %d",ret);
    return ret;
  }
  if (strlen(binlog_opt_val)) binlog_opt= WSREP_SST_OPT_BINLOG;

  make_wsrep_defaults_file();

  ret= snprintf (cmd_str, cmd_len,
                 "wsrep_sst_%s "
                 WSREP_SST_OPT_ROLE" 'donor' "
                 WSREP_SST_OPT_ADDR" '%s' "
                 WSREP_SST_OPT_AUTH" '%s' "
                 WSREP_SST_OPT_SOCKET" '%s' "
                 WSREP_SST_OPT_DATA" '%s' "
                 " %s "
                 " %s '%s' "
                 WSREP_SST_OPT_GTID" '%s:%lld'"
                 "%s",
                 method, addr, sst_auth_real, mysqld_unix_port,
                 mysql_real_data_home, wsrep_defaults_file,
                 binlog_opt, binlog_opt_val,
                 uuid, (long long) seqno,
                 bypass ? " "WSREP_SST_OPT_BYPASS : "");
  my_free(binlog_opt_val);

  if (ret < 0 || ret >= cmd_len)
  {
    WSREP_ERROR("sst_donate_other(): snprintf() failed: %d", ret);
    return (ret < 0 ? ret : -EMSGSIZE);
  }

  if (!bypass && wsrep_sst_donor_rejects_queries) sst_reject_queries(FALSE);

  pthread_t tmp;
  sst_thread_arg arg(cmd_str);
  mysql_mutex_lock (&arg.lock);
  ret = pthread_create (&tmp, NULL, sst_donor_thread, &arg);
  if (ret)
  {
    WSREP_ERROR("sst_donate_other(): pthread_create() failed: %d (%s)",
                ret, strerror(ret));
    return ret;
  }
  mysql_cond_wait (&arg.cond, &arg.lock);

  WSREP_INFO("sst_donor_thread signaled with %d", arg.err);
  return arg.err;
}

wsrep_cb_status_t wsrep_sst_donate_cb (void* app_ctx, void* recv_ctx,
                                       const void* msg, size_t msg_len,
                                       const wsrep_gtid_t* current_gtid,
                                       const char* state, size_t state_len,
                                       bool bypass)
{
  /* This will be reset when sync callback is called.
   * Should we set wsrep_ready to FALSE here too? */

  wsrep_config_state.set(WSREP_MEMBER_DONOR);

  const char* method = (char*)msg;
  size_t method_len  = strlen (method);
  const char* data   = method + method_len + 1;

  char uuid_str[37];
  wsrep_uuid_print (&current_gtid->uuid, uuid_str, sizeof(uuid_str));

  int ret;
  if (!strcmp (WSREP_SST_MYSQLDUMP, method))
  {
    ret = sst_donate_mysqldump(data, &current_gtid->uuid, uuid_str,
                               current_gtid->seqno, bypass);
  }
  else
  {
    ret = sst_donate_other(method, data, uuid_str, current_gtid->seqno,bypass);
  }

  return (ret > 0 ? WSREP_CB_SUCCESS : WSREP_CB_FAILURE);
}

void wsrep_SE_init_grab()
{
  if (mysql_mutex_lock (&LOCK_wsrep_sst_init)) abort();
}

void wsrep_SE_init_wait()
{
  while (SE_initialized == false)
  {
    mysql_cond_wait (&COND_wsrep_sst_init, &LOCK_wsrep_sst_init);
  }
  mysql_mutex_unlock (&LOCK_wsrep_sst_init);
}

void wsrep_SE_init_done()
{
  mysql_cond_signal (&COND_wsrep_sst_init);
  mysql_mutex_unlock (&LOCK_wsrep_sst_init);
}

void wsrep_SE_initialized()
{
  SE_initialized = true;
}